Descriptive epidemiology of selected heritable birth defects in Texas.

BACKGROUND: Few population-based studies exist on descriptive epidemiologic characteristics of rare heritable birth defects. The number of birth defect cases in the Texas Birth Defects Registry (one of the largest active birth defects surveillance systems in the world) enabled us to examine six different heritable disorders (aqueductal stenosis, infantile polycystic kidney disease, achondroplasia, thanatophoric dwarfism, chondrodysplasia/dwarfism not otherwise specified (NOS), and osteogenesis imperfecta) for a variety of descriptive demographic variables. METHODS: The Texas Birth Defects Registry was used to identify infants or fetuses with heritable birth defects. Crude prevalence rates were calculated and Poisson regression was used to test the association of each demographic variable (e.g., maternal age) with each of the selected genetic birth defects. RESULTS: White non-Hispanics exhibited higher rates of achondroplasia and osteogenesis imperfecta than other race/ethnic groups. Lower maternal education level and to a lesser extent, paternal education level, was associated with higher rates of several disorders. The birth prevalence rate for achondroplasia decreased from 1999 through 2006. CONCLUSION: The use of a large birth defects registry provides a sufficient count of cases to perform some basic epidemiologic analysis on selected rare heritable birth defects.

Achondroplasia in diverse Jewish and Arab populations in Israel: clinical and molecular characterization.

BACKGROUND: Achondroplasia is the most frequent form of disproportionate short stature, characterized by rhizomelic shortening of the limbs. This disorder is inherited as an autosomal dominant trait, although most of the cases are sporadic, a result of a de novo mutation. A recurrent glycine to arginine mutation at codon 380 (G380R) in the transmembrane domain of the fibroblast growth factor receptor 3 gene was found to cause achondroplasia among different populations. This is most uncommon in other autosomal dominant genetic diseases. OBJECTIVES: To determine whether this mutation is also common among Jewish patients from diverse ethnic groups and among the Arab population in Israel. METHODS: We examined the G380R mutation (G > A and G > C transition) and the mutation G375C (G > T transition at codon 375) in 31 sporadic patients and in one family diagnosed clinically to have achondroplasia. RESULTS: We found the G > A transition at codon 380 in 30 of our patients and the G > C transition in one patient. We were not able to detect any of the three mutations in two patients with an atypical form of achondroplasia. CONCLUSIONS: Our results further support the unusual observation that nucleotide 1138 of the FGFR3 gene is the most mutable nucleotide discovered to date across different populations.